Liubo
A board widely played in China from the Warring States period through the Han dynasty. By the Tang dynasty, how it was played had been lost. This is the counterpart to Ur. Ur came back because a single clay tablet describing its rules had survived. Liubo boards and pieces have been excavated, and the tomb of the Marquis of Haihun even yielded over a thousand bamboo strips referring to how it was played (reported in 2019) — yet the rules still cannot be reconstructed with certainty. What is known only goes as far as: a stick or dice were thrown, and six pieces were moved. Then, in July 2026, one more surprise was announced. A liubo board excavated in 2022 from a Han tomb in Xi'an turned out not to be lacquered wood or stone at all, but lines simply carved into a plain brick. A game thought to belong to kings and nobles had also been buried with commoners. Boards get found. People get found. And still, there are boards whose rules alone never come back.